Simplified artificial leg structure with articulated knee joint

ABSTRACT

An artificial leg with ankle operated knee joint having a pair of V belts fixed at one end extending about a grooved upper knee element and a pivotal cam actuated by ankle rods for locking the knee joint in a limited pivoted position. An auxiliary mechanical lock limits knee joint pivoting and, upon manual operation, locks the leg in stiff alignment.

' United States Patent [191 Minor SIMPLIFIED ARTIFICIAL LEG 360,446 4/1887 STRUCTURE WITH ARTICULATED KNEE 766,686 3/1904 JOINT 2,282,952 5/1942 3,453,663 7/1969 -[76] Inventor: Orval L. Minor, 1220 Tasman Drive, No. 306, Sunnyvale, Calif. Primary Examiner-Ronald L. Fn'nks 94086 Attorney, Agent, or Firm-Gregg, Hendricson, Caplan 22 Filed: Mar. 6, 1975 Beck [21] Appl. No.2 555,850 [57] ABSTRACT An artificial leg with ankle operated knee joint having [52] US. Cl. 3/25; 3/27; 3/26 a p f V el s fixe t one end extending about a [51] Int. Cl. A61F 1/04; A61F 1/08 grooved pp r n m n an a pivo l cam actu- [58] Field of Search 3/2229, 2 ated y nkle rods for locking the knee joint in a limited pivoted position. An auxiliary mechanical lock [56] References Cited limits knee joint pivoting and, upon manual operation,

UNITED STATES PATENTS locks the leg in stiff alignment. 49,253 8/1865 Fosterm: 3/25 5 Claims, 3 g g I J ,4: a. [I l/I l 07 is. I I I, m6 1 f /f I i F 32/! I 26 m l 3/ I! 9/ l a: 1.4 44 7 p :3: (J 0 M I x: g il 1 35 J 215 47 ."l

\ 6P 75 a 4 6 j I 5;

7; I d a: a; 7 67 I? i .4

I ALL I I [451 Nov, 4, 1975 U.S. Patent Nov. 4, 1975 SIMPLIFIED ARTIFICIAL LEG STRUCTURE WITH ARTICULATED KNEE JOINT BACKGROUND OF INVENTION Following the marked improvement of artificial legs resulting from research during and following World War II, it became conventional for artificial legs including knee and ankle joints to walk with the upper and lower leg portions in alignment. Most advanced artificial legs are operated from the upper end with the lower leg freely swinging forwardly during a step and being locked in alignment with the upper leg as the weight is placed on the leg. Although artificial legs with ankle and knee joints are markedly superior to the old wooden legs, they commonly fail to provide the capability of walking under a number of different circumstances. Thus, for example, walking up an inclined surface is normally very difficult with an artificial leg of conventional construction and also walking along an inclined surface such as the side of a hill is almost impossible. A further problem often encountered by users of artificial legs is the possibility of collapse of the knee joint when walking on uneven terrain or making unusual movements. A marked improvement in artificial legs is set forth in US. Pat. No. 3,453,663 and reference is herein made thereto for a further background description and identification of certain major advancements in the field.

The present invention comprises an improvement upon the artificial leg of the above-identified patent. The present invention provides the capability of the artificial leg of such patent and, in addition, provides for a positive locking of the knee joint under operating conditions by the utilization of a pair of fixed belts. There is also provided herein a mechanical knee joint lock eliminating possible knee joint pivoting and being operable to controllably lock the knee joint to override the automatic controls of the invention.- There is furthermore provided here, by the relocation of elements and the elimination of certain elements, a materially simplified structure of even greater commercial applicability.

SUMMARY OF INVENTION The present invention provides an ankle joint pivotally connecting a foot element to uprights of a lower leg portion of an artificial leg and a knee joint pivotally connecting the uprights to an upper knee element. V- belts disposed about the upper knee element are secured to a pivotal cam on the uprights of the lower leg element.

Actuators are pivotally mounted ahead and behind the ankle joint and are connected to the cam for pivot ing the cam with pivoting of the foot to thus lock the knee joint for a predetermined pivoting of the foot when body weight is applied to the foot.

There is also provided herein a mechanical stop incorporated in the knee joint to physically limit the possible degree of pivoting of such joint. The mechanical stop is also controllably operable by the wearer of the limb to physically lock the upper and lower leg portions in alignment in order that the leg will be adapted for negotiating particularly difficult terrain or the like.

DESCRIPTION OF FIGURES LII FIG. 3 is a partial sectional view taken in the plane 3-3 of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT Considering now a preferred embodiment of the present invention and referring to the drawings, there will be seen to be illustrated an artificial foot 11 with which the present invention is adapted to cooperate and which in itself may be conventional except for the ankle portion. The invention includes an ankle joint 12 incorporating a pair of uprights or side plates 13 and 14 pivotally mounted upon an upright element 16 atop the foot 11 by means of the shaft 17. The uprights or side plates are laterally displaced, as illustrated in FIG. 2, and may include outwardly tapered or inclined central portions in order to generally conform to the lateral configuration of a human leg. At the upper ends of the side plates 13 and 14 there is provided an upper knee element 18 pivotally connected between the side plates by a transverse shaft 19 to form a knee joint 21. The upper knee element 18 is adapted to be affixed to the upper leg of a wearer of the limb and this may be accomplished in a conventional manner. A cosmetic cover 22 is preferably provided to enclose the lower leg portion 23 of the present invention, with this cover being appropriately configured to accommodate relative movement of the foot, lower leg portion and upper knee element. The cover may be formed of a plastic or the like and removably mounted.

The present invention provides simplified means for controlling the operation of the knee joint 21 by operation of the ankle joint 12. To this end there are provided a pair of V-belts 26 and 27 having the first ends thereof fixed to the uprights l3 and 14 below the knee joint as by means of a crosspiece 28 secured to the uprights with a clamping plate 29 attached thereto by screws or bolts 31 for clamping the ends of the belts between the two plates.

The V-belts 26 and 27 extend from the first clamped ends thereof, as described above, upwardly about a knurled roller 32 rotatably mounted between the side plates 13 and 14 and thence about the upper knee element 18 within grooves 36 and 37 formed by a cylindrical transverse portion of the upper knee element 18. The V-belts fit within the grooves in the upper knee element in a snug fit and thence extend downwardly of the lower leg element beneath the knee joint into fixed engagement with a pivotally mounted cam 41.

The cam 41 of the present invention includes arms 42 mounted upon a shaft 43 that is rotatably mounted between the side plates 13 and 14 and a curved cam surface element 44 over which the belts 26 and 27 are firmly secured to the under side of the cam 41 as by means of a bar or plate 47 bolted to the cam arms 42 and clamping the ends of the V-belts against the cam arms. Additionally the belts are secured to the curved cam surface 44 by a clamp 48 extending across the belts and bolted to the cam surface element 44. With this arrangement upward pivoting of the cam pushes the belts upwardly to free them from clamping relation to the grooves 36 and 37 so that the knee joint pivots freely.

The pivotal cam 41 is operated by actuators 51 and 52 having lower links 53 and 54, respectively, pivotally mounted on transverse shafts or axles 56 and 57 of the upper foot element 16. One of the axles S6 is disposed rearwardly of the shaft 17 and one of the axles 57 is disposed ahead of this shaft. The actuator 51 includes a rod 61 threaded into the link 53 and locked thereto by a locknut 62 with a cylinder 63 at the upper end of the rod having an elongated slot 64 transversely therethrough. The other actuator 52 is similarly constituted in having a rod 66 threaded into the link 54 and locked thereto by a locknut 67 with an elongated cylindrical fixture 68 at the upper end of the rod with an elongated slot 69 transversely through such fixture. A transverse shaft 71 extends between the outer ends of the cam arms 42 and through the slots 64 and 69 in the actuators 51 and 52.

The cylinders 63 and 68 are secured to the upper ends of the rods 61 and 66 by threaded engagement therewith and normally left-hand threads are adequate to maintain the cylinder positions. Nuts 72 and 73 may be welded on the rods 61 and 66, respectively, below the cylinders to provide a wrench purchase. The actuators 51 and 52 are urged downwardly of the artificial limb and to this end there is provided a spring compression plate 76 mounted between the uprights 13 and 14 with compression springs 77 and 78 about the rods 61 and 66, respectively, beneath such plate. Considering the rod 61, it will be seen that the spring 77 is compressed beneath the plate 76 and bears upon a washer 81 about the rod with a flex nut threaded beneath the washer to maintain the washer position on the rod. Similarly, the spring 78 on the rod 66 is compressed between the plate 76 and a washer 82 on the rod with a flex nut threaded on the rod beneath the washer to hold the latter in position. The compression springs 77 and 78 will be seen to operate upon the actuators to force the rods thereof downwardly toward the foot. Provision is also made for adjusting the amount of movement which the actuators may make and this is accomplished by threading a set screw 86 into the outer end of the fixture 68 with a locknut thereon so that the set screw extends into the upper end of the slot 69 and thus effectively controls the length of the slot. Similarly, a set screw 87 may be threaded into the outer end of the fixture 63 with a locknut about the set screw and the set screw extending longitudinally into the outer end of the slot 64 to adjust the effective length thereof.

Considering further the pivotal cam 41 of the present invention, it is noted that provision is made for adjusting the cam position and such adjusting means 91 may include a fixed bar 92 mounted between the uprights 13 and 14 and having a set screw 93 threaded therethrough for engagement with the rear of the cam portion having the cam surface 44 on the front thereof. A locknut 94 is threaded on the set screw to fix the adjusted position of the cam as controlled by the set screw. The cam is urged against the adjusting means 91 by a pair of tension springs 96 and 97 hooked onto the shaft 71 on the cam arms and secured to the side plates 13 and 14, respectively, below the shaft. It will be seen that these springs 96 and 97 pivot the cam means 41 in a clockwise direction as viewed in FIG. 1 of the drawings, so that the cam bears upon the cam stop or adjusting means 91. The springs 96 and 97 may be considered cam return springs, which pivot the cam into engagement with the adjusting means in the normal or unoperated condition of the leg.

There is also provided herein an adjustable knee stop 101 which may be comprised as a plate 102 pivotably mounted between the side plates 13 and 14 beneath the knee element 18 and extending upwardly for physical engagement with the knee element 18 or a pin thereon extending across an opening in the under side of the knee element. One or more adjusting screws 103 with locknuts 104 thereon are threaded through the plate 102 for engagement with the side plates 13 and 14 or extensions thereof in order to adjustably set the position of the knee stop so that the knee element 18 may only be pivoted a predetermined amount in a clockwise direction. This prevents any possibility of knee collapse.

The present invention furthermore provides an improvement in the knee element, wherein the element may be physically locked against any pivoting. The above-described elements provide for an automatic control of pivoting of the leg about the knee element, however under certain circumstances, as in a strong wind, tall grass or water, or in activities such as golf, it is desirable to lock the leg and knee together in aligned or bent position. To this end, there is herein provided, as illustrated in FIG. 3, a locking pin 106 extending laterally through the side plate 13 into an arcuate cutout 107 of about 55 on the side surface of the knee element 18. The locking pin 106 normally is maintained in an intermediate position as illustrated in FIG. 3, for example by a snap ring 108 fitting in a groove about the pin and adapted to resiliently expand into a mating groove about the opening in the side plate 13. In this position the inner end of the locking pin 106 fits within the arcuate cutout 107 in the knee element 18, so that normal pivoting of leg with respect to knee as in walking is possible. Under the circumstances wherein it is desirable to physically lock the leg and knee in alignment, the locking pin 106 may be pressed further inwardly to move the inner end of the pin into the mating depression 109 in the knee element. This depression is located in the position to be engaged by the locking pin only when the knee element 18 and leg are in alignment. A second snap spring 111 on the locking pin may be provided to maintain the locking pin in inserted position until it is physically withdrawn. A third or fully retracted locking pin position is provided by a third snap ring 112 at substantially the inner end of the pin 106 whereby the pin may be withdrawn entirely from the slot 107 to allow full knee joint pivoting of 'about for kneeling or the like. In this simple manner it is possible for the knee joint to lock with upper and lower portions in alignment, so the wearer of the invention may negotiate particularly difficult terrain or particularly difficult maneuvers, and yet the wearer may readily operate this locking pin to release the lower leg at will. With the locking pin retracted into the position of FIG. 3, automatic operation of the invention is possible for the inner end of the locking pin merely moves about the arcuate cutout 107 during such operations. It will furthermore be noted that this locking pin additionally provides a further mechanical stop to limit the extent of knee rotation, as on steep inclines, for example.

There has been described above a preferred physical embodiment of the present invention and attention is now invited to operation thereof. It is first noted that the V-belts 26 and 27 extending about the mating grooves 36 and 37 in the knee element 18, are adapted to firmly grip the knee element upon tightening of the belts, so as to lock the knee element 18 and the lower leg 23 together. The actuating bars 51 and 52 are pivotally mounted one ahead of and one behind the ankle joint, and operatively engage the cam means 41 so that any time the foot is rotated about the ankle joint, the cam 41 is pivoted to tighten the V-belts 26 and 27, which have their opposite ends secured at 28-29. This provides a solid state against which the knee stress takes over, commensurate with the weight of the user, rather than backward through all the linkage to the ankle flex as in my prior structure noted above. This then draws these belts tightly into the grooves 36 and 37 to lock together the lower leg and knee element. As soon as the force originally pivoting the foot is removed, i.e., body weight is lifted, the springs 77 and 78 return the foot to the illustrated unpivoted position to remove the pressure of the cam on the V-belts, and to push the belts upwardly out of clamping relation to the grooves 36 and 37 to thus release the knee element from the lower leg, so that the lower leg is free to swing about the knee element. Actual walking is accomplished in the same manner as described in my above identified patent, however the structure of the present invention is materially simplified and improved thereover. Additionally, the manually operable knee lock hereof materially extends the capabilities of the invention. Although automatically controlled artificial legs comprise an enormous advance over stiff wooden legs" or the like, it is recognized that the human wearer sometimes desires to or is obligated to traverse difficult terrain and thereby creates conditions that cannot be adequately handled by automatic controls. Under these conditions the present invention provides for mechanical locking of the knee joint by a manually operable lock so that the wearer may negotiate particularly difficult terrain or the like without fear of falling. This manually operable knee lock in combination with the improved artificial leg structure extends the capabilities of artificial legs to the material benefit of the wearer.

Although the present invention has been described above in connection with a single preferred embodiment of the invention, it is not intended to limit the invention to the particular terms of description or details of illustration for it will be apparent to those skilled in the art that modifications and variations are possible within the true scope of the present invention.

What is claimed is:

1. An improved artificial leg comprising:

an artificial foot,

a lower leg pivotally connected to said artificial foot at an ankle joint,

an upper knee element adapted for connection to the upper leg of a person and having a cylindrical portion with a pair of circumferential grooves thereabout,

a knee joint shaft secured across the upper end of said lower leg portion through the cylindrical portion of said upper knee element for rotatably mounting said upper knee element to define a knee joint,

a pair of tension belts disposed one in each circumferential groove in said upper knee element with a first end of each belt secured to said lower leg beneath said knee joint,

a cam element pivotally mounted on said lower leg below said knee joint and having the second end of said belts connected thereto, and

a pair of spring-loaded actuators pivotally mounted on said foot one ahead of and one behind said ankle joint and extending into engagement with said cam element for pivoting the cam upon pivoting of the ankle joint to thereby tighten said belts about said upper knee element and lock said knee joint.

2. The artificial leg of claim 1 further defined by said lower leg including a pair of rigid side plates carrying said knee joint shaft and having a transverse member secured between said side plates beneath said knee joint with the first ends of said belts extending over said transverse member to wrap said belts about more than halfway around the circumferential grooves in the cylindrical member of said upper knee element to maximize the gripping action of the belts on the upper knee element when said belts are tightened by said cam element.

3. The artificial leg of claim 1 further defined by each of said actuators having a heavy compression spring about the lower end thereof and compressed between a longitudinally adjustable projection on the actuator and a spring compression plate affixed to the lower leg above the spring for urging said ankle joint into unpivoted position.

4. The artificial leg of claim 1 further defined by a manually operable mechanical stop mounted upon said lower leg portion and movable into a mating depression in said upper knee element with the knee joint unpivoted to physically lock the knee joint against movement.

5. The artificial leg of claim 4 further defined by said upper knee joint having an arcuate cutout in a side thereof with said depression at one end thereof and said mechanical stop including a pin extending into said arcuate cutout and manually movable therefrom into said depression. 

1. An improved artificial leg comprising: an artificial foot, a lower leg pivotally connected to said artificial foot at an ankle joint, an upper knee element adapted for connection to the upper leg of a person and having a cylindrical portion with a pair of circumferential grooves thereabout, a knee joint shaft secured across the upper end of said lower leg portion through the cylindrical portion of said upper knee element for rotatably mounting said upper knee element to define a knee joint, a pair of tension belts disposed one in each circumferential groove in said upper knee element with a first end of each belt secured to said lower leg beneath said knee joint, a cam element pivotally mounted on said lower leg below said knee joint and having the second end of said belts connected thereto, and a pair of spring-loaded actuators pivotally mounted on said foot one ahead of and one behind said ankle joint and extending into engagement with said cam element for pivoting the cam upon pivoting of the ankle joint to thereby tighten said belts about said upper knee element and lock said knee joint.
 2. The artificial leg of claim 1 further defined by said lower leg including a pair of rigid side plates carrying said knee joint shaft and having a transverse member secured between said side plates beneath said knee joint with the first ends of said belts extending over said transverse member to wrap said belts about more than halfway around the circumferential grooves in the cylindrical member of said upper knee element to maximize the gripping action of the belts on the upper knee element when said belts are tightened by said cam element.
 3. The artificial leg of claim 1 further defined by each of said actuators having a heavy compression spring about the lower end thereof and compressed between a longitudinally adjustable projection on the actuator and a spring compression plate affixed to the lower leg above the spring for urging said ankle joint into unpivoted position.
 4. The artificial leg of claim 1 further defined by a manually operable mechanical stop mounted upon said lower leg portion and movable into a mating depression in said upper knee element with the knee joint unpivoted to physically lock the knee joint against movement.
 5. The artificial leg of claim 4 further defined by said upper knee joint having an arcuate cutout in a side thereof with said depression at one end thereof and said mechanical stop including a pin extending into said arcuate cutout and manually movable therefrom into said depression. 